#include <iostream>

// We have been using std::cout throughout this course.
//
// The identifier std::cout refers to an object representing
// the standard output stream. Like other objects, std::cout
// has member functions that can be called using the '.'
// operator:
//
//     object.member_function( arguments )
//
// For example:
//
//     std::cout.precision( 10 );
//
// calls the member function 'precision' on the std::cout
// object.
//
// Some useful member functions of std::cout include:
//
// precision:
//    https://en.cppreference.com/cpp/io/ios_base/precision
//
// width:
//    https://en.cppreference.com/cpp/io/ios_base/width
//
// fill:
//    https://en.cppreference.com/cpp/io/basic_ios/fill

int main() {
  double pi{ 3.14159265358979323846 };

  // precision(...)
  //
  // The precision controls the number of digits used when
  // displaying floating-point values. The default is 6.
  //
  // Unlike width(...), the precision remains in effect for
  // subsequent floating-point output until it is changed.
  std::cout << "Using the default precision:" << std::endl;
  std::cout << pi << std::endl;

  std::cout.precision( 10 );

  std::cout << std::endl
            << "After std::cout.precision( 10 ):"
            << std::endl;
  std::cout << pi << std::endl;
  std::cout << pi/3.0 << std::endl;

  // Calling precision() with no argument returns the
  // current precision.
  std::cout << std::endl
            << "The current precision is "
            << std::cout.precision() << "."
            << std::endl;

  // width(...)
  //
  // The width specifies the minimum number of characters
  // to use for the next formatted output operation.
  //
  // Unlike precision(...), the width normally returns to
  // zero after that output operation.
  std::cout << std::endl
            << "Using std::cout.width( 10 ):"
            << std::endl;

  std::cout << "[";
  std::cout.width( 10 );
  std::cout << 42;
  std::cout << "]" << std::endl;

  std::cout << "[";
  std::cout.width( 10 );
  std::cout << 123456;
  std::cout << "]" << std::endl;

  // Notice that the width applied above does not continue
  // to apply to subsequent output.
  std::cout << "[" << 42 << "]" << std::endl;

  // fill(...)
  //
  // The fill character is used when the requested width is
  // greater than the number of characters being displayed.
  //
  // The default fill character is a space.
  std::cout << std::endl
            << "Changing the fill character:"
            << std::endl;

  std::cout.fill( '.' );

  std::cout << "[";
  std::cout.width( 10 );
  std::cout << 42;
  std::cout << "]" << std::endl;

  std::cout << "[";
  std::cout.width( 10 );
  std::cout << 123456;
  std::cout << "]" << std::endl;

  // Calling fill() with no argument returns the current
  // fill character.
  std::cout << std::endl
            << "The current fill character is '"
            << std::cout.fill() << "'."
            << std::endl;

  // Restore the usual fill character.
  std::cout.fill( ' ' );

  return 0;
}